Dragon Frizell has surgery after low blow

St George Illawarra forward Tyson Frizell has undergone surgery on his testicles after copping a nasty accidental blow in Saturday's NRL loss to North Queensland.

Frizell reeled out of an attempted tackle on Cowboys fullback Jordan Kahu, with the NSW State of Origin star going under the knife in Townsville on Saturday night.

The Dragons said the exact nature of his injury had not been diagnosed and he was a chance to line up for Thursday's clash with South Sydney.

Frizell took to Instagram on Sunday, alongside a picture of him in a hospital bed with his son, to say: "Not an ideal start to the 2019 season but so grateful to have you (wife Sammy) and the little man by my side to put a smile on my face."

If Frizell has suffered a ruptured testicle, it could see him miss up to six weeks.

His loss would be a huge blow for Paul McGregor's side, particularly given Jack de Belin has been stood down indefinitely and Korbin Sims will miss another two games due to suspension.

Frizell was moved to lock from the second row for their season opener and his absence will stretch the side's depth.

"On Saturday night in our game against the North Queensland Cowboys, Tyson Frizell copped a blow to his testes," Dragons head of performance Nathan Pickworth said.

"Following the game, we investigated further with follow up scans which unfortunately resulted in surgery being performed in Townsville.

"Tyson this morning is in a good condition and in good spirits. We will update as more news comes to hand later in the week."